5. The self-releasing flexible intermediate transfer member of claim 2,
wherein said material is present in an amount by weight of from about 5
wt % to about 25 wt %.

6. The self-releasing flexible intermediate transfer member of claim 1,
further comprising a polysiloxane surfactant.

7. The self-releasing flexible intermediate transfer member of claim 6,
wherein said surfactant is present in an amount from about 0.05% by
weight to about 2% by weight.

8. An imaging device comprising the intermediate transfer member of claim
1.

9. A method of making a flexible member for an imaging device, comprising
applying a film-forming solution comprising a polyamic acid and an
amine-neutralized phosphate or phosphoric acid to a mold to form said
member; and removing said member from said mold, wherein a releasing
agent is not used and said member self-releases from said mold.

10. The method of claim 9, wherein said solution further comprises a
polysiloxane surfactant.

11. An intermediate transfer member produced by the method of claim 9.

Description:

FIELD

[0001] A novel flexible member composition, such as, an intermediate
transfer belt (ITB), such as, an endless belt having an annular main
body, for use in an electrophotographic imaging device is provided. The
imaging device produces a fixed toner image on a recording medium.

BACKGROUND

[0002] In the electrophotographic imaging arts, an image forming apparatus
forms a static latent image by exposure of a surface of a charged
photosensitive member to patterns of light, develops that static latent
image to form a toner image, and finally transfers the toner image to a
recording medium, such as, a paper, at a predetermined transfer position,
thereby forming an image thereon.

[0003] One such image forming apparatus employs, in the process of image
formation and development, an endless belt that is stretched around
support rolls, and which circulates and moves as a unit, carrying the
formed toner image to a transfer position. Alternatively, the endless
belt can operate as a unit that transfers the recording medium to a
transfer position.

[0004] In an image forming apparatus that forms a color image, because
toner images of individual different colors are superimposed on one
another, an endless belt can be used as a unit that carries the toner
images of different color which are sequentially applied or received in
building the final composite color image. An endless belt also can be
used as a unit for transferring a recording medium that sequentially
receives toner images of different color. See, for example, U.S. Pat. No.
7,677,848 and U.S. Publ. No. 20100279217, herein incorporated by
reference in entirety.

[0005] Image forming apparatus with high endurance that are capable of
withstanding, for example, temperature variation and high volume output,
are desirable. Hence, materials to enhance flexible member performance
and preparation are desirable.

[0006] Endless flexible belts can be made by producing a film on or
attached to a mold, mandrel or form. A film-forming solution or
composition is applied to a form by, for example, dipping, spraying, flow
coating or other known method, and the solution or composition can be
dispersed or distributed to form a thin film, for example, by
centrifugation over the inner wall of a hollow form, for example, a
cylindrical form.

[0007] When using such forming or molding methods, the dried or cured film
must be separated from the molding form, and preferably with minimal
stress, deformation, damage and the like to the film. Moreover, it is
desirable that the film be easily removed from the molding form.

[0008] In the electrophotographic arts, it is beneficial, if not
necessary, for a flexible member surface that carries a charge and a
latent image to be regular with minimal imperfections, such as, pits,
valleys, indentations, waves, wrinkles, dimples and the like, an erose
surface is not beneficial if maximal image fidelity is desired.

SUMMARY

[0009] According to aspects disclosed herein, there is provided a
film-forming composition for making flexible members for use in
electrophotography, such as, a flexible image transfer member, such as,
an intermediate transfer belt (ITB), wherein a coating solution for
forming same comprises a polyamic acid and an internal release agent that
facilitates removal of the formed film from a mold, mandrel, form and the
like.

[0010] In embodiments, an internal release agent can comprise an ester or
ether of a phosphate or a phosphoric acid, and the phosphate or
phosphoric acid, which may be derivatized, may be stabilized with a
non-aromatic amine, and which further can comprise a sulfur or
sulfur-containing moiety.

[0011] An embodiment comprises a film-forming composition, such as, a
coating solution for making a flexible image transfer member, such as, an
intermediate transfer belt (ITB), optionally comprising a polysiloxane
surfactant.

[0012] Another disclosed embodiment comprises an imaging or printing
device comprising a film comprising a polyimide obtained from a polyamic
acid composition and an internal release agent, and optionally, a
polysiloxane surfactant.

DETAILED DESCRIPTION

[0013] As used herein, the term, "electrophotographic," or grammatic
versions thereof, is used interchangeably with the term, "xerographic."
In some embodiments, such as, in the case of forming a color image,
often, individual colors of an image are applied sequentially. Thus, a,
"partial image," is one which is composed of one or more colors prior to
application of the last of the colors to yield the final or composite
color image. "Flexible," is meant to indicate ready deformability, such
as, observed in a belt, web, film and the like, that, for example, are
adaptable to operate and for use with, for example, rollers.

[0014] For the purposes of the instant application, "about," is meant to
indicate a deviation of no more than 20% of a stated value or a mean
value. Other equivalent terms include, "substantial," and, "essential,"
or grammatic forms thereof.

[0015] In electrophotographic (xerographic) reproducing or imaging
devices, including, for example, a digital copier, an image-on-image
copier, a contact electrostatic printing device, a bookmarking device, a
facsimile device, a printer, a multifunction device, a scanning device
and any other such device, a printed output is provided, whether black
and white or color, or a light image of an original is recorded in the
form of an electrostatic latent image on an imaging device component, for
example, which may be present as an integral component of an imaging
device or as a replaceable component or module of an imaging device, and
that latent image is rendered visible using electroscopic, finely
divided, colored or pigmented particles, or toner. The imaging device
component can be a flexible member.

[0016] A flexible member can comprise an intermediate transfer member,
such as, an intermediate transfer belt (ITB), a fuser belt, a pressure
belt, a transfuse belt, a transport belt, a developer belt and the like.
Such members can comprise a single layer or plural layers, such as, a
support layer and one or more layers of particular function.

[0017] Hence, such transfer members can be present in an
electrophotographic image forming device or printing device. In the case
of an ITB, a photoreceptor is electrostatically charged and then is
exposed to a pattern of activating electromagnetic radiation, such as,
light, which alters the charge on the surface of an imaging device
component leaving behind an electrostatic latent image thereon. The
electrostatic latent image then is developed at one or more developing
stations to form a visible image or a partial image by depositing finely
divided electroscopic colored, dyed or pigmented particles, or toner, for
example, from a developer composition, on the surface of the imaging
component. The resulting visible image on the photoreceptor is
transferred to an ITB for transfer to a receiving member or for further
developing of the image, such as, building additional colors on
successive partial images. The final image then is transferred to a
receiving member, such as, a paper, a cloth, a polymer, a plastic, a
metal and so on, which can be presented in any of a variety of forms,
such as, a flat surface, a sheet or a curved surface. The transferred
particles are fixed or fused to the receiving member by any of a variety
of means, such as, by exposure to elevated temperature and/or elevated
pressure.

[0018] An intermediate transfer member also finds use in color systems and
other multi-imaging systems. In a multi-imaging system, more than one
image is developed, that is, a series of partial images. Each image is
formed on the photoreceptor, is developed at individual stations and is
transferred to an intermediate transfer member. Each of the images may be
formed on the photoreceptor, developed sequentially and then transferred
to the intermediate transfer member or each image may be formed on the
photoreceptor developed and transferred in register to the intermediate
transfer member. See, for example, U.S. Pat. Nos. 5,409,557; 5,119,140;
and 5,099,286, the contents of which are incorporated herein by reference
in entirety.

[0019] It can be desirable to minimize transferring developer or developer
carrier to the receiving member, that is, for example, a paper.
Therefore, it can be advantageous to transfer the developed image on a
photoreceptor to an intermediate transfer web, belt, roll or member, and
subsequently to transfer the developed image from the intermediate
transfer member to a permanent or ultimate substrate or receiving member.

[0020] To obtain quality image transfer, that is, to minimize image shear,
the displacement of a transfer member due to disturbance during transfer
member driving can be reduced by limiting the thickness of the support or
substrate, for example, to about 50 μm. Thus, the thickness of the
substrate or support can be from about 50 μm to about 150 μm or
from 70 μm to about 100 μm.

[0021] In the instant disclosure, a substrate of interest is a polyimide
that is obtained from a polyamic acid derivative of a carboxylate
reagent, such as, a polycarboxylate reagent that on reaction, drying
and/or curing, forms a polyimide suitable for use as a flexible member in
an imaging device.

[0022] Polyamic acid derivatives are available commercially, for example,
U-VARNISH-A or U-VARNISH-S (UBE America Inc.) and a Pyre-ML®, such
as, RC-5019 or 5083 (Industrial Summit Technology Co.), or can be made
practicing methods known in the art, see, for example, U.S. Pat. No.
7,812,084.

[0023] When synthesizing a polyamic acid, suitable carboxylates are those
comprising plural carboxyl groups for reacting with a polyamine in a
polar solvent.

[0027] Examples of polar organic solvents that can be used for preparing a
polyamic acid of interest include sulfoxide solvents, such as,
dimethylsulfoxide and diethylsulfoxide, formamide solvents, such as,
N,N-dimethylformamide and N,N-diethylformamide, acetamide solvents, such
as, N,N-dimethylacetamide and N,N-diethylacetamide, pyrrolidone solvents,
such as, N-methyl-2-pyrrolidone and N-vinyl-2-pyrrolidone, phenol-based
solvents, such as, phenol, o-cresol, m-cresol, p-cresol, xylenol,
halogenated phenols and catechol, ether solvents, such as,
tetrahydrofuran, dioxane and dioxolane, alcohol solvents, such as,
methanol, ethanol and butanol, cellosolve solvents, such as, butyl
cellosolve, hexamethylphosphoramide, γ-butylolactone, and the like.
The solvent may be used alone or in combination of two or more.

[0028] The reaction temperature during polymerization of a polyamic acid
can be in the range of from about 0° C. to about 80° C.

[0029] The film-forming composition comprising a polyamic acid derivative
comprises an internal release agent, such as, a non-aromatic
amine-neutralized phosphate, an amine-neutralized phosphoric acid ester,
an amine-neutralized phosphate or phosphoric acid containing a sulfur or
a sulfur-containing moiety and so on. Examples of suitable commercially
available lubricants include a VANLUBE®, such as 672 or 9123 (R.T.
Vanderbilt Co., Inc.) and an ADDITIN®, such as, RC3740, RC3760 or
RC3775 (Rhein Chemie Corp.).

[0030] The internal releasing agent can be present in the film-forming
composition in an amount of from about 0.1 wt % to about 5 wt %, from
about 0.5 wt % to about 3 wt %, from about 0.8 wt % to about 2 wt %, or
about 1 wt %.

[0031] The film-forming composition comprising a polyamic acid derivative
optionally can comprise a polysiloxane surfactant to enhance surface
uniformity, smoothness and so on. Suitable examples include polyether
and/or polyester modified polydimethylsiloxanes, which can be
hydroxylated, or silicone modified polyacrylates. Examples of
commercially available silicone surfactants include a BYK® additive,
such as, 310, 330 and 375, and BYK®-SILCLEAN 3700.

[0032] The polysiloxane surfactant can be present in the film-forming
composition in an amount of from about 0.05 wt % to about 2 wt %, from
about 0.01 wt % to about 1 wt %, from about 0.02 wt % to about 0.5 wt %,
or about 0.3 wt %.

[0033] A transfer member or device generally is one where the surface
destined to carry an image has a low surface energy, i.e., material
comprising an electrically conducting agent dispersed thereon having a
contact angle of not less than about 70° or at least about
70° with respect to a water droplet as represented by wettability
by water. The term, "wettability by water," as used herein is meant to
indicate the angle of contact of a material constituting the surface
layer as a specimen with respect to a water droplet.

[0034] Electrical property regulating materials can be added to the
substrate or to a layer superficial thereto to regulate electrical
properties, such as, surface and bulk resistivity, dielectric constant
and charge dissipation. In general, electrical property regulating
materials can be selected based on the desired resistivity of the film.
High volume fractions or loadings of the electrical property regulating
materials can be used so that the number of conductive pathways is always
well above the percolation threshold, thereby avoiding extreme variations
in resistivity. The percolation threshold of a composition is a volume
concentration of dispersed phase below which there is so little particle
to particle contact that the connected regions are small. At higher
concentrations than the percolation threshold, the connected regions are
large enough to traverse the volume of the film, see, for example, Scher
et al., J Chem Phys, 53(9)3759-3761, 1970, who discuss the effects of
density in percolation processes.

[0035] Particle shape of the electrical property regulating material can
influence volume loading. Volume loading can depend on whether the
particles are, for example, spherical, round, irregular, spheroidal,
spongy, angular or in the form of flakes or leaves. Particles having a
high aspect ratio do not require as high a loading as particles having a
relatively lower aspect ratio. Particles which have relatively high
aspect ratios include flakes and leaves. Particles which have a
relatively lower aspect ratio are spherical and round particles.

[0036] The percolation threshold is practically within a range of a few
volume % depending on the aspect ratio of the loadent. For any particular
particle resistivity, the resistivity of the coated film can be varied
over about one order of magnitude by changing the volume fraction of the
resistive particles in the layer. The variation in volume loading enables
fine tuning of resistivity.

[0037] The resistivity varies approximately linearly to the bulk
resistivity of the individual particles and the volume fraction of the
particles in the support or layer. The two parameters can be selected
independently. For any particular particle resistivity, the resistivity
of the reinforcing member can be varied over roughly an order of
magnitude by changing the volume fraction of the particles. The bulk
resistivity of the particles preferably is chosen to be up to three
orders of magnitude lower than the bulk resistivity desired in the
member. When the particles are mixed with the support or layer in an
amount above the percolation threshold, the resistivity of the resulting
reinforcing member can decrease in a manner proportional to the increased
loading. Fine tuning of the final resistivity may be controlled on the
basis of that proportional increase in resistivity.

[0038] The bulk resistivity of a material is an intrinsic property of the
material and can be determined from a sample of uniform cross section.
The bulk resistivity is the resistance of such a sample multiplied by the
cross sectional area divided by the length of the sample. The bulk
resistivity can vary somewhat with the applied voltage.

[0039] The surface or sheet resistivity (expressed as ohms/square,
Ω/quadrature) is not an intrinsic property of a material because
that metric depends on material thickness and contamination of the
material surface, for example, with condensed moisture. When surface
effects are negligible and bulk resistivity is isotropic, the surface
resistivity is the bulk resistivity divided by the reinforcing member
thickness. The surface resistivity of a film can be measured without
knowing the film thickness by measuring the resistance between two
parallel contacts placed on the film surface. When measuring surface
resistivity using parallel contacts, one uses contact lengths several
times longer than the contact gap so that end effects do not cause
significant error. The surface resistivity is the measured resistance
multiplied by the contact length to gap ratio.

[0040] Particles can be chosen which have a bulk resistivity slightly
lower than the desired bulk resistivity of the resulting member. The
electrical property regulating materials include, but are not limited to
pigments, quaternary ammonium salts, carbons, dyes, conductive polymers
and the like. An example of a carbon black is Special Black 4 (Evonik
Industries). Electrical property regulating materials may be added in
amounts ranging from about 1% by weight to about 50% by weight of the
total weight of the support or layer or from about 5% to about 25% by
weight of the total weight of the support or layer.

[0041] Thus, for example, carbon black systems can be used to make a layer
or layers conductive. That can be accomplished by using more than one
variety of carbon black, that is, carbon blacks with different, for
example, particle geometry, resistivity, chemistry, surface area and/or
size. Also, one variety of carbon black or more than one variety of
carbon black can be used along with other non-carbon black conductive
fillers.

[0042] An example of using more than one variety of carbon black, each
having at least one different characteristic from the other carbon black,
includes mixing a structured black, such as, VULCAN® XC72, having a
steep resistivity slope, with a low structure carbon black, such as,
REGAL 250R®, having lower resistivity at increased filler loadings.
The desired state is a combination of the two varieties of carbon black
which yields a balanced controlled conductivity at relatively low levels
of filler loading, which can improve mechanical properties.

[0043] Another example of mixing carbon blacks comprises a carbon black or
graphite having a particle shape of a sphere, flake, platelet, fiber,
whisker or rectangle used in combination with a carbon black or graphite
with a different particle shape, to obtain good filler packing and thus,
good conductivity. For example, a carbon black or graphite having a
spherical shape can be used with a carbon black or graphite having a
platelet shape. The ratio of carbon black or graphite fibers to spheres
can be about 3:1.

[0044] Similarly, by use of relatively small particle size carbon blacks
or graphites with relatively large particle size carbon blacks or
graphite, the smaller particles can orient in the packing void areas of
the polymer substrate to improve particle contact. As an example, a
carbon black having a relatively large particle size of from about 1
μm to about 100 μm or from about 5 μm to about 10 μm can be
used with a carbon black having a particle size of from about 0.1 μm
to about 1 μm or from about 0.05 μm to about 0.1 μm.

[0045] In another embodiment, a mixture of carbon black can comprise a
first carbon black having a BET surface area of from about 30 m2/g
to about 700 m2/g and a second carbon black having a BET surface
area of from about 150 m2/g to about 650 m2/g.

[0046] Also, combinations of resistivity can be used to yield a shallow
resistivity change with filler loading. For example, a carbon black or
other filler having a resistivity of about 10-1 to about 103
ohms-cm, or about 10-1 to about 102 ohms-cm can be used in
combination with a carbon black or other filler having a resistivity of
from about 103 to about 107 ohms-cm.

[0047] In preparing a polyimide endless belt for an image-forming
apparatus by using a polyamic acid composition of the disclosure, the
amount of carbon black can be in the range of about 0 to about 20 parts
by weight, or about 5 to about 10 parts by weight, with respect to 100
parts by weight of the polyamic acid in the polyamic acid firm-forming
composition.

[0048] Other fillers, in addition to carbon blacks, can be added to the
polymer, resin or film-forming composition and dispersed therein.
Suitable fillers include metal oxides, such as, magnesium oxide, tin
oxide, zinc oxide, aluminum oxide, zirconium oxide, barium oxide, barium
titanate, beryllium oxide, thorium oxide, silicon oxide, titanium dioxide
and the like; nitrides such as silicon nitride, boron nitride, and the
like; carbides such as titanium carbide, tungsten carbide, boron carbide,
silicon carbide, and the like; and composite metal oxides such as zircon
(ZrO2.Al2O3), spinel (MgO.Al2O3), mullite
(3Al2O3.2SiO2), sillimanite (Al2O3SiO2),
and the like; mica; and combinations thereof. Optional fillers can be
present in the polymer/mixed carbon black coating in an amount of from
about 20% to about 75% by weight of total solids, or from about 40% to
about 60% by weight of total solids.

[0049] The resistivity of the coating layer can be from about 107 to
about 1013Ω/quadrature, from about 108 to about
1012Ω/quadrature or from about 109 to about
1011Ω/quadrature.

[0050] In another embodiment, the layer has a dielectric thickness of from
about 1 μm to about 10 μm or from about 4 μm to about 7μ.

[0051] The hardness of the coating can be less than about 85 Shore A, from
about 45 Shore A to about 65 Shore A, or from about 50 Shore A to about
60 Shore A.

[0052] In another embodiment, the surface can have a water contact angle
of at least about 60°, at least about 75°, at least about
90° or at least about 95°.

[0053] Transfer members can be prepared using methods known in the art.
The polyamic acid composition is prepared by mixing and dispersing the
components in a dispersing machine or a mixing vessel and then the
mixture is applied to the form, mandrel or mold, such as, one made from a
resin, a glass, a ceramic, stainless steel and so on, for example, using
methods such as those described in U.S. Pat. Nos. 4,747,992, 7,593,676
and 4,952,293, which are hereby incorporated herein by reference. Other
techniques for applying materials include liquid and dry powder spray
coating, dip coating, wire wound rod coating, flow coating fluidized bed
coating, powder coating, electrostatic spraying, sonic spraying, blade
coating and the like. If a coating is applied by spraying, spraying can
be assisted mechanically and/or electrically, such as, by electrostatic
spraying.

[0054] The film is allowed to dry and/or to cure at a suitable
temperature; and then is removed from the mold. As the film of interest
is self-releasing, it is not necessary to add a releasing agent, such as,
a silicone-based or a fluorine-based composition, to the mold, mandrel or
form before applying the film-forming composition thereto or thereon. By,
"self-release," is meant that a cured or formed film releases from a mold
or form without or with minimal intervention.

[0055] In such cases where a film-forming solution or composition is
applied to a form, a mandrel, a mold and the like, removal of the formed
film intact and with minimal damage, with little difficulty or
intervention or both are desirable. The polyamic acid reagent in the
solution added directly to the form, mandrel, mold and the like
facilitates or enhances such subsequent facile removal of the dried
and/or cured film therefrom.

[0056] The film can be seamless or can be used to make a seamed member, as
known in the art.

[0057] Various aspects of the embodiments of interest now will be
exemplified in the following non-limiting examples.

EXAMPLES

Example 1

[0058] A 14/85.45/0.5/0.05 ratio by weight of Special Black 4 carbon black
(Evotik Industries), polyamic acid of pyromellitic acid/4,4-oxydianiline,
Pyre-ML RC5019 (Industrial Summit Technology Corp.), VANLUBE 672 (R.T.
Vanderbilt Co.) and BYK 310 were dissolved in N-methyl-2-pyrrolidone at a
rate of about 13 wt % solids. After ball milling for 120 minutes, the
solution was coated on a stainless steel substrate with a 10-mil Bird
bar, and dried and cured at 125° C. for 30 minutes, 190° C.
for 30 minutes and then at 320° C. for 60 minutes.

[0059] The film released readily from the stainless steel mold. The film
had a thickness of about 80 μm, had a smooth surface and there was no
curl.

Example 2

[0060] The ITB of Example 1 was tested for various properties, along with
those of a commercially available device, using materials and methods
known in the art. The results are provided in the table below.

[0061] The ITB of interest also was tested for thermal expansion as known
in the art. The ITB of interest has a CTE of 47 ppm, comparable to that
of the Fuji Xerox ITB.

[0062] All references cited herein are herein incorporated by reference in
entirety.

[0063] It will be appreciated that variants of the above-disclosed and
other features and functions, or alternatives thereof, may be combined
with other and different systems or applications. Various presently
unforeseen or unanticipated alternatives, changes, modifications,
variations or improvements subsequently may be made by those skilled in
the art to and based on the teachings herein without departing from the
spirit and scope of the embodiments, and which are intended to be
encompassed by the following claims.

Patent applications by Jin Wu, Pittsford, NY US

Patent applications by XEROX CORPORATION

Patent applications in class ION-EXCHANGE POLYMER OR PROCESS OF PREPARING

Patent applications in all subclasses ION-EXCHANGE POLYMER OR PROCESS OF PREPARING